You don’t have to be Biggest Loser to to win war on weight

WEIGHT-LOSS ads and television shows regularly profile people who have transformed their lives through major losses of 30 kilograms or more.

These weight-loss ambassadors try to inspire us to do the same by telling us they feel more alive, they can play with their kids and their confidence has grown - now they can fit into a size ten dress.

These messages are echoed by health promotion agencies that encourage us to fight the obesity epidemic - and the rise of chronic diseases - by achieving and maintaining a healthy weight.

Major weight loss certainly sounds like a good plan if you're overweight or obese and serious about improving your health. But the reality is it's incredibly difficult to lose 30 kg, and even if you do, it's even harder to keep off in the long term.

Australia's National Health and Medical Research Council (NHMRC) draft guidelines for the management of overweight and obesity recommend starting with a more modest weight loss goal of 5% or 5kg, whichever is higher.

For people who are overweight or have crossed over into obesity (with a body mass index or BMI of 25 to 35), a 5% to 10% weight loss is enough to improve your health and reduce risk factors for chronic conditions such as type 2 diabetes and heart disease.

After two years, your risk of developing type 2 diabetes diabetes will have halved.

Some heavier people who have a BMI over 30 may need to lose 15% to 20% of their weight to get the same improvement in risk profile.

Managing expectations

The strongest predictor of dropping out of a weight-loss program is starting off with an expectation of losing a really large amount of weight.

So, one of the practical problems in starting the weight-loss journey is that people rarely want to limit their weight loss to 5% of their starting weight.

This 2005 study of 1,785 obese Italians is a good example. The group had a mean BMI of 38. Their maximum or "dream" weight loss goal was 32% of their starting body weight, and their minimum "acceptable" weight loss was 23%.

This weight loss expectation is five to six times more weight than is needed to improve their health, well-being and quality of life and to reduce their medication needs.

It's therefore important for health professionals to manage their patients' weight-loss expectations.

Start with a goal of 10% of initial body weight and focus on health improvement, reductions in medication use and improved quality of life. Once this has been achieved, then you can revise the goals.

Losing weight and keeping it off

The good news is that we now know a lot more about how to successfully maintain a reasonable weight loss.

A 2011 study of more than 5,000 Americans with existing type 2 diabetes found that almost one quarter had maintained a weight loss of 10% or more of their starting weight after four years.

Importantly, success was associated with attending more treatment sessions, reporting greater adherence to the lower kilojoule diet and burning more kilojoules in physical activity.

A review of the long-term weight loss trials found a mean weight loss of 3kg to 6kg (3% to 6%) was maintained in trials that extended to four years.

It's important to note that participants regain some weight once treatment the ends.

This is completely normal, and should be expected because as soon as you ease off on the kilojoule restriction or exercise routine needed for weight loss, your weight will creep back up.

Therefore, based on current research, the definition of successful long-term weight loss is being able to maintain a weight loss of 5% of your starting body weight for more than a year.

Bariatric surgery is the only intervention where weight losses greater than 10% body weight have been maintained for 10 years or longer.

Step by step weight loss

Weight loss is never easy but a little common sense can go a long way in helping you achieve your goals. If you are planing to lose weight, here are some things to keep in mind:

Being physically active each day, reducing your daily kilojoules intake, maintain healthy eating habits on weekends and holidays, and jumping on weight rebounds when they're small will all increase your chance of success.

Clare Collins is a Professor in Nutrition and Dietetics at University of Newcastle